Remove and reorder unused imports across the project for cleaner and more consistent code structure

backend/app/core/database_async.py

@@ -10,6 +10,7 @@ from contextlib import asynccontextmanager
 from typing import AsyncGenerator
 
 from sqlalchemy import text
+from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.ext.asyncio import (
     AsyncSession,
     AsyncEngine,
@@ -17,7 +18,6 @@ from sqlalchemy.ext.asyncio import (
     async_sessionmaker,
 )
 from sqlalchemy.ext.compiler import compiles
-from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import DeclarativeBase
 
 from app.core.config import settings